manual exchange meaning in English

人工电话局
人工交换机
手动交换

Requiring an operator in order to function ( " a manual exchange " ; " a manual executive " )
说明为了正常操作需要有操作人员的工作（如人工交换、人工执行）。
It has the function of conference calling , manual exchange and pcm exchange etc . based on the brief analysis of working state of the pbx , we set up a frame model of the software , and the main arithmetic which make up of this model are given
本文首先介绍了各部分的硬件实现，在控制软件的设计中通过建立合理的软件模型来解决系统的实时性和并发性的问题，最后给出了此类软件的cad系统设计的方法。